Many designs of solar panels, particularly plate panels, have been proposed and built. Such collectors vary in their construction materials, working fluid coupling, and geometrical arrangements. A good description of known solar-energy panels can be found in the following references: Energy Primer Solar, Water Wind and Biofuels, published by Fricke-Parks-Press, Inc. 1974, PP. 6-9; Solar Energy Thermal Properties published by John Wiley & Sons, Inc., 1974, PP. 162-168; and U.S. Pat. Nos. 3,102,532, 3,902,474, 3,923,038, 3,908,631 and 3,254,643. In known collectors, the solar radiation absorbing member is typically a metal sheet (usually aluminum or copper painted black) which is heated by impinging solar radiation, and this heat is conducted by the working fluid (usually water) which contacts the metal or flows through passages in the metal. The water being heated is then pumped to a heat exchanger wherein house water or air is to be warmed. However, the known designs of such collectors exhibit numerous known disadvantages, chief among which are the following:
1. absorption of incident solar radiation occurs on a relatively smooth surface whereat reflection losses can be significant;
2. thermal energy generated in metallic surfaces pass by conduction to the periphery of the collector's structure and therefore there is a need for substantial insulation of the collector to minimize conductive heat losses to its surroundings;
3. relatively poor conduction of heat from the metal to the working fluid in the metal's passages;
4. corrosion and general deterioration of the collector's construction materials frequently takes place; and
5. fabrication costs are substantial, especially since most known solar collectors are expensive to mass produce.